INTERNAL COMBUSTION ENGINE CONTROL DEVICE

PROBLEM TO BE SOLVED: To suppress calculation load on a fuel behavior model.SOLUTION: A control device of an internal combustion engine according to the invention controls arithmetic operation means to perform an arithmetic operation relating to a fuel behavior using a fuel behavior model that is a model of a behavior of fuel injected from a port injector. The control device performs the arithmetic operation by this arithmetic means until the passing time since the injection of the fuel into cylinders of the internal combustion engine stops reaches a predetermined stop determination period, and controls the arithmetic means to stop the arithmetic operation until the injection of the fuel restarts if the passing time reaches the predetermined stop determination period.